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    <title>empty</title>
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    <center>Scilab Function</center>
    <div align="right">Last update : April 1993</div>
    <p>
      <b>empty</b> -  ([]) empty matrix</p>
    <h3>
      <font color="blue">Description</font>
    </h3>
    <p>
      <tt>
        <b> [] </b>
      </tt> denotes the empty matrix. It is uniquely defined
    and has 0 row and 0 column, i.e. <tt>
        <b> size([]) =[0,0] </b>
      </tt>.
    The following convenient conventions are made:</p>
    <p>
      <tt>
        <b> [] * A = A * [] = [] </b>
      </tt>
    </p>
    <p>
      <tt>
        <b> [] + A = A + [] = A</b>
      </tt>
    </p>
    <p>
    [ [], A] = [A, []] = A
    <tt>
        <b> inv([]) =[] </b>
      </tt>
    </p>
    <p>
      <tt>
        <b> det([])=cond([])=rcond([])=1, rank([])=0</b>
      </tt>
    </p>
    <p>
    Matrix functions return <tt>
        <b>[]</b>
      </tt> or an error message
    when there is no obvious answer. Empty linear systems 
    (<tt>
        <b> syslin</b>
      </tt> lists) may have several rows or columns.</p>
    <h3>
      <font color="blue">Examples</font>
    </h3>
    <pre>

s=poly(0,'s'); A = [s, s+1]; 
A+[], A*[]
A=rand(2,2); AA=A([],1), size(AA)
svd([])
w=ssrand(2,2,2); wr=[]*w; size(wr), w1=ss2tf(wr), size(w1)
 
  </pre>
    <h3>
      <font color="blue">See Also</font>
    </h3>
    <p>
      <a href="matrices.htm">
        <tt>
          <b>matrices</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="poly.htm">
        <tt>
          <b>poly</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="../strings/string.htm">
        <tt>
          <b>string</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="boolean.htm">
        <tt>
          <b>boolean</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="rational.htm">
        <tt>
          <b>rational</b>
        </tt>
      </a>,&nbsp;&nbsp;<a href="../elementary/syslin.htm">
        <tt>
          <b>syslin</b>
        </tt>
      </a>,&nbsp;&nbsp;</p>
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